If one class of society is obliged, in order to live, to take any price for its services, while another can abstain from such action thanks to resources at its disposal which, however, are not necessarily due to any social superiority, the second has an unjust advantage over the first at law. In other words, there cannot be rich and poor a birth without there being unjust contracts.

Emile Durkheim: Selected Writings (ed. Cambridge University Press, 1972) - ISBN: 9780521097123